High quality digital cameras have to a large extent replaced film cameras. However, like film cameras, with digital cameras much attention has been placed by the camera industry on the size and quality of lenses which are used on the camera. Individuals seeking to take quality photographs are often encouraged to invest in large bulky and often costly lenses for a variety of reasons. Among the reasons for using large aperture lenses is their ability to capture a large amount of light in a given time period as compared to smaller aperture lenses. Telephoto lenses tend to be large not only because of their large apertures but also because of their long focal lengths. Generally, the longer the focal length, the larger the lens. A long focal length gives the photographer the ability to take pictures from far away.
In the quest for high quality photos, the amount of light which can be captured is often important to the final image quality. Having a large aperture lens allows a large amount of light to be captured allowing for shorter exposure times than would be required to capture the same amount of light using a small lens. The use of short exposure times can reduce blurriness especially with regard to images with motion. The ability to capture large amounts of light can also facilitate the taking of quality images even in low light conditions. In addition, using a large aperture lens makes it possible to have artistic effects such as small depth of field for portrait photography.
While large lenses have many advantages with regard to the ability to capture relatively large amounts of light compared to smaller lenses, support large zoom ranges, and often allow for good control over focus, there are many disadvantages to using large lenses. Large lenses tend to be heavy requiring relatively strong and often large support structures to keep the various lenses of a camera assembly in alignment. The heavy weight of large lenses makes cameras with such lenses difficult and bulky to transport. Furthermore, cameras with large lenses often need a tripod or other support to be used for extended periods of time given that the sheer weight of a camera with a large lens can become tiresome for an individual to hold in a short amount of time. In addition to weight and size drawbacks, large lenses also have the disadvantage of being costly.
For a lens of a digital camera to be useful, it needs to be paired with a device which detects the light passing through the lens and converts it to pixel (picture element) values. A megapixel (MP or Mpx) is one million pixels. The term is often used to indicate the number of pixels in an image or to express the number of image sensor elements of a digital camera where each sensor element normally corresponds to one pixel. Multi-color pixels normally include one pixel value for each of the red, green, and blue pixel components.
In digital cameras, the photosensitive electronics used as the light sensing device is often either a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) image sensor, comprising a large number of single sensor elements, each of which records a measured intensity level. In many digital cameras, the sensor array is covered with a patterned color filter mosaic having red, green, and blue regions in an arrangement. In such a filter based approach to capturing a color image, each sensor element can record the intensity of a single primary color of light. The camera then will normally interpolate the color information of neighboring sensor elements, through a process sometimes called demosaicing, to create the final image. The sensor elements in a sensor array using a color filter are often called “pixels”, even though they only record 1 channel (only red, or green, or blue) of the final color image due to the filter used over the sensor element.
While small focal length lenses paired with relatively high resolution sensors have achieved widespread commercial success in cell phones and pocket cameras, they often leave their owners longing for better picture quality, e.g., picture quality that can only be achieved with a larger pixel area and a larger lens opening to collect more light.
Smaller sensors require smaller focal length lenses (hence smaller lenses) to frame the same scene from the same point. Availability of high pixel count small sensors means that a smaller lens can be used. However, there are a few disadvantages to using smaller sensors and lenses. First, the small pixel size limits the dynamic range of the sensor as only a small amount of light can saturate the sensor. Second, small lenses collect less total light which can result in grainy pictures. Third, small lenses have small maximum apertures which make artistic effects like small depth of field for portrait pictures not possible.
In view of the above discussion, it should be appreciated that there is a need for new photographic methods and apparatus which can provide some combination of the benefits commonly associated with large lenses, e.g., a relatively large lens area for capturing light, with at least some of the benefits of small focal length lenses, e.g., compact size. Additionally, it would be desirable if some of the disadvantages such as limited dynamic range and/or depth of field associated with small focal length lenses could be avoided and/or such advantages reduced without requiring the use of large lenses.
In particular, there is a need for improved methods and apparatus for supporting zoom operations. It would be desirable if at least some of the methods and/or apparatus provide one or more of the benefits associated with use of a large lens. It would be preferable but not absolutely necessary that the one or more benefits could be provided without the need for a large heavy lens extending out way beyond the body of the camera.